The double copy of the multipole expansion

TL;DR

This paper demonstrates how the classical double copy relates multipole moments of vacuum type D gravity fields to gauge and scalar theories using twistor methods, confirmed by Kerr metric results.

Contribution

It introduces a twistor-based approach to map multipole moments in gravity to gauge and scalar theories within the classical double copy framework.

Findings

Multipole moments of vacuum type D gravity fields are mapped to gauge and scalar theories.

Results are consistent with previous Kerr metric analyses.

Provides physical intuition for the double copy mechanism.

Abstract

We consider the classical double copy, that relates solutions of biadjoint scalar, gauge and gravity theories. Using a recently developed twistor expression of this idea, we use well-established techniques to show that the multipole moments of arbitrary vacuum type D gravity fields are straightforwardly mapped to their counterparts in gauge and biadjoint scalar theory by the single and zeroth copies. We cross-check our results using previously obtained results for the Kerr metric. Our results provide further physical intuition of how the double copy operates.